Jonathan Demme’s “The Manchurian Candidate” opens and closes with a loud, overbearing remake of Creedence Clearwater Revival’s classic “Fortunate Son.” The cover, performed by Wyclef Jean, lacks the raw intensity and anger of the original recording, although the song is so well written that the new version, even with all the unnecessary upgrades, reminds us of why the song was so incredible in the first place. Which makes it, then, the perfect song for this movie.

Why would anyone in their right mind want to remake The Manchurian Candidate, anyway? The 1962 film, adapted (far more faithfully than the remake) from Richard Condon’s novel, is a bona fide classic, John Frankenheimer’s finest hour, and one of the greatest movies Hollywood has ever produced. It is a flawless thriller in every regard. So why update it?

The answer, I think, may lie in the fact that Demme is directing. Demme’s last film was “The Truth About Charlie,” a dreadful revamping of the Stanley Donen masterpiece “Charade.” Of that film, Demme once thought that nobody would really care if he remade it, as the film had no big following; he was wrong, of course, but even going on that logic, why would he then feel that an updated “Manchurian” - one of the most famous of all classic thrillers - would go without protest? Maybe Demme’s handling of “Charlie” gave him the courage to tackle an even more beloved picture. Or maybe he’s just crazy.

Either way, we’re stuck with a remake, and while it’s unfair to compare the two movies, I can’t help it. It’s impossible to judge the new “Manchurian” on its own merits, as we’ve already seen the story told once before, and that time it was perfect. All we can do with this new version is count the differences and take note of how a few changes can ruin an otherwise amazing story.

Change number one: Raymond Shaw (played this time by Liev Schreiber) is no longer the programmed assassin he was in the original. There’s a scene late in the remake, after Raymond has killed someone, that has his handlers complaining that he wasn’t made to be a hitman - even though that was more or less the point last time.

What he is instead is a potential Vice Presidential candidate (yup, that’s a big change) who’s been programmed through brainwashing and, to give the remake a high tech kick, mind-controlling brain implants. The culprits are not a group of Communists but the folks of Manchurian Global, a Halliburton-esque megacorporation who are in the pockets of half of the government. But that’s not enough, it seems, and they want, through an overly complicated scheme, to place into power “the first privately owned and operated Vice President.” (Don’t we already have one of those?)

I say the scheme is overly complicated because unlike the original, which highlighted a similar scheme but as an effort to have a Communist takeover of the presidency, this new version of the plot seems pointless. If Manchurian Global controls so much of the government, why bother with the mind control? They’re not satisfied with the apparently effective bribes, payouts, and back door deals as they are? What we get is a muddy patchwork of corporate conspiracy dealings that don’t entirely click, and not the airtight political scheming of the original.

Change number two: Raymond’s mother (Meryl Streep) is now a big name Senator. Huh? The power of the character in the 1962 film was that she was the puppetmaster to her weak husband, that she was a Lady Macbeth who manipulated in the shadows, controlling the power as a means of taking it for herself without publicly doing so. In the remake, the mother is such a powerful, popular figure that we wonder why she’s pulling the strings of her son’s campaign instead of simply rising up and taking it for herself. Why make her son veep when she could get more done if she had the job? It’s a flawed attempt to make the character more timely.

Change number three: Marco. Played by Denzel Washington, this updated main character is no longer the quiet, haunted hero but a quiet, haunted loony. To give the remake a more modern feel of conspiracy nuts and post-war stress, this new Marco steals too much from the overall plot. The film then becomes less about Shaw the killer and the political agenda behind him, and more about Marco the nutcase, to whom nobody will listen. This kind of character may be more in step with a current notion of paranoia and schizophrenia, but it comes off like a copy of Mel Gibson in “Conspiracy Theory.” Despite a fine performance from Washington, who handles the character’s various mood swings with his usual skill, it’s a poorly constructed character.

Change number four: The dreams. In Frankenheimer’s film, the dream sequences were the most memorable moments, frightening in their calm complexity. Demme, deciding copying these classic scenes would be a mistake, instead pours on overly loud, heavily edited bits of chaos that assault the audience.

But in the original, we never saw just how the soldiers were programmed, adding a layer of tense mystery to the proceedings. Here, in the remake, the answer is given; it’s an attempt to scare us with an unsettling visual assault. By having it seen, some of the impact is lost. There are no chances for the hushed chills of the original, and we wind up with crazed memories that are too much, too little - that is, too much effort, too little impact.

That’s how the entire movie goes, really. This new “Manchurian” is louder, more forceful, less willing to let the suspense come to a slow boil on its own. Consider the train sequence, in which Marco meets potential love interest Rosie (Kimberly Elise, who previously stunk up the Washington vehicle “John Q” and who fares about the same here). In the original, the odd dialogue and careful chemistry of Frank Sinatra and Janet Leigh made it a remarkable moment, one that created an instant bond between two characters while still managing to create a sense of unease. In the remake, the scene feels rushed. There’s chemistry missing between Washington and Elise, and their delivery of the dialogue - copied word for word from the first movie - never clicks. (And it should say something that half the dialogue of the original has been removed, probably to speed up the pacing.)

There’s also the question of Rosie’s motives. For the original, we wonder if she’s up to anything, why she would fall for this stranger. We never get an answer, the result being a subtle feeling of uncertainty that adds to the tension of the film. The remake, however, gives us more answer than we need, and it ruins a great riddle that should have remained unanswered. Rosie’s motives feel dropped in as an obligatory twist, and the effect backfires; we’d be more on edge had we not known the truth.

There are other changes, some major, that cannot be discussed here without spoiling the ending; needless to say, the final scenes in this remake are completely lacking in tension. Unlike the shock and terror of the Frankenheimer version, Demme’s finale is a slow build to no surprise.

There’s one more problem, and that’s in the movie’s unintentional lack of believability. One of the reasons the 1962 version works so well is that Frankenheimer treated his project with almost documentary-like realism. Compare this with Demme’s version. We watch the fakey newscasts, phony political conventions, and falsely staged rallies, none of which are ever convincing. Nothing takes you out of a movie like too-fake news on the TV. Or what of the contrived postscript, which tidies up all loose ends with eye-rolling computers-can-do-anything hokiness? Oh, and when Rosie gives her number as “El Dorado 5-9970,” no amount of backpedaling (“I like to say it the old fashioned way,” she meekishly explains later) makes up for the ridiculousness of the line. The new “Manchurian” is a movie that’s repeatedly reminding the audience that they’re watching a movie.

“Manchurian” isn’t as big of a disaster as “The Truth About Charlie,” mainly thanks to a more workable screenplay, a clear vision from Demme, and, most of all, decent performances from the major players. Yet even the cast pales in comparison to the original film, and no matter how well Scheiber and Washington handle the material, I still spent most of the time wishing for Sinatra and Harvey instead. And as hard as Streep may try, she’s simply no match for Angela Lansbury, whose turn in the original “Manchurian” ranks among the finest screen performances ever given.

There are people who will enjoy this “Manchurian” as a nifty disposable thriller, and most of them are, most likely, folks who have never seen the original film. This remake is cheap, forgettable movie; the 1962 version is great cinema. A remake was wholly unnecessary, especially when it’s as sloppy and inefficient a thriller as this one turned out to be. Here’s a remake so limp that I’m surprised Mark Wahlberg isn’t in it. Do yourself a big favor: skip this uneven retread and check out the original instead. You’ll be glad you did.